Surface coating



Patented Apr. 16, 1935 UNITED STATES PATENT OFFICE a v 1,998,099 mmsnsni ifz pfi 1:! atomic:

Hercules Powder Company, Wilmington, Del, a a 7 corporation of Delaware Y No Dr-a This invention relates to a surface coatingand more particularly relates to a laminated surface coating for various materials.

The surface coating in accordance with this 5 invention comprises a base coat including rosin,

which coat may merely be a surface coat or may impregnate the body of a material to be coated as well as surface coat the material, and a thin overcoat including nitrocellulose.

The coating in accordance with this invention willbegreaseproofandwillhavethehistre and appearance of athick nitrocellulose coating. The coating lends itself admirably to the coating of sheet material as paper, etc., and to the coat- .1s ingoffibreboardaskraftboardcartonboard.

30 any suitable solvent which may be removed, as,

for example, by evaporation. Alternatively, for example,whenthebasecoatismerely acoating, ias,forexample,onthecoatingofcartonboard, thebasecoatcomsybeappliedina a5 molten state.

7 Thetoporovercoatappliedasacoatingover thebasecoatwill'berelaiivelythinandwlllcomprise essentially nitrocellulose which maybe applied over the base coat in the form of a solution 40, or any suitable solvent. The overcoat in addition to nitrocellulose may contain various ingredients, but desirabhr will be free of the gums and plasticizers ordinarily used-in lacquers slnce,

while their inclmion is not prohibited, they will 45 tendtomaketheovercoatsticky.

I The ingredients comprising the base coat may be included in widely varying proportions, however the most results will be obtained with compositions comprising, for exam- 50 ple, rosin 75-95% and rubber 5-25%, or rosin-80- -99% and 140%. It will be noted that where paraiiine isusedrubber may be included also and that where imtion is to be avoided the parafllne content of the composition limit- 55 ed to a maximum of about 5%. 'I'tae'b'ose coat cotton,.having a viscosity of about second, in

Application May as, 1932, Serial No. 613,562

5 claims. (cl. 91-68) when applied in a molten condition may be applied at a temperature of, my, 100-300? F. by any suitable method, as by transfer from a hot roll, dipping into a pan containing the molten composition and removal of excess by means of a second hot roll or 5 by a doctor" blade. When the undercoat is applied in the form of a solution the solution may be, for example, a 540% solution in benzol, toluol, or other suitable solvent and the application may be by dipping or other desirable method. 10

The base coat having been applied to the material, the overcoat comprising essentially nitrocellulose as ior example, nitrocotton in solution or any well known solvent, as ethyl acetate, butyl acetate, acetone, and coating or diluent, if de- 15 sired, is applied byany suitable method as, for example, by dipping, spraying, etc.

- Before applying the overcoat the base coat will desirably bewarmed to smooth its surface and, as j will be obvious, the viscosity of the nitrocellulose solution for application to form the overcoat will be regulated as desired by control of the amount of, solvent or solvent mixture and/or bythe use of a nitrocellulose of desired viscosity characteristic.

As more specifically illustrative, for example,

a satisfactory base coating may have the m1- lowing formula:

' Rosin 85 97 3o Rubber 15 Paramne 3 a satisfactory overcoat will be-formed by the application of a solution of, say, about nitroethyl acetate or acetone.

As will be appreciated the base-coat composition will adhere to the surface of the material.

as paper, carton board, etc., to which it is ap- 4o plied or' in which it is impregnated andthe overand will have thelustre of a thick nitrocellulose coating. Thebase cost will not bleed through the overcoat and the overcoat will provide a lustrous smooth finish having substantial moisture resistance. I

Materials, as, for example, paper carton board. 5 etc., which merely. coated or coated and impregnoted, as described above, will be found of great advantage variously and especially in connection with the wrapping or of foodstufls.

Having now fully de'scribedmy invention. what I claim and desire to protect by Letters Patent is:

1. In combination a base having a surface, a

coating formed on a'surtaceoi' the base comprising a major proportion of rosin and a minor proportion of a substance from the group consisting of rubber and paramn and a coating comprising dominatingly nitrocellulose superimposed on said first mentioned coating.

2. In combination a base having a surface. a coating formed on a surface or the base comprising rosin 75-95% and-rubber 15-25% and a coating composition comprising dominatingly nitrocellulose superimposed on said first mentioned coating.

3. In combination a base having a statue, a coating formed on a surface or the base comprising rosin 80-99% and parailln 1-20% and a coating comprising div nitrocellulose superimposed on said first mentioned coating.

4. In combination a. felted material forming abase,acoatingtormedonasurtaceotthebase comprising a major proportion of rosin and a minor proportion of a substance from the group consisting of rubber and parai'lin and a' coating comprising dominatingly nitrocellulose superimposed on said first mentioned coating.

5. In combination a paper forming a base, a coating termed on a surface or the base comprising a major proportion of rosin and a minor proportion 01' a substance from the group consisting of rubber and paramn and a coating comprising dominatingly nitrocellulose superimposed l5 

